http://cb-antennas.com/?page_id=965
Pages of reading to do if you are interested in the AVANTI sigma IV.
Pages of reading to do if you are interested in the AVANTI sigma IV.
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sigma4 article is online
- Thread starter bob85
- Start date
Realising it is a rather long article it will probably take some time to read.
I believe all claims have been mentioned.
If not please do let me know.
Questions or improvements are welcomed, debates without "foundation" will be avoid.
Hoping it can contribute the debate.
Happy reading
Kind regards, H.
I believe all claims have been mentioned.
If not please do let me know.
Questions or improvements are welcomed, debates without "foundation" will be avoid.
Hoping it can contribute the debate.
Happy reading
Kind regards, H.
Henry, this is a very well done article with plenty of good images and to the point.
I will be referring to it for sure. Some of the ideas are beyond my understanding, but I would expect no less.
Thanks for your time and efforts.
I will be referring to it for sure. Some of the ideas are beyond my understanding, but I would expect no less.
Thanks for your time and efforts.
Great article Henry,
Its by far the most informative & best explained article i ever read on CB antennas,
Thank you for taking the time and effort to gather the info, model, explain in words & pictures,
and do actual field tests,
best regards.
Its by far the most informative & best explained article i ever read on CB antennas,
Thank you for taking the time and effort to gather the info, model, explain in words & pictures,
and do actual field tests
,best regards.
Great article Henry,
Its by far the most informative & best explained article i ever read on CB antennas,
Thank you for taking the time and effort to gather the info, model, explain in words & pictures,
and do actual field tests
best regards.
Hey Bob, how did you know that Henry's report would make me happy?
I didn't know for sure Eddie, i had a fair idea where it was heading,
i gave you a clue when i posted that some of your ideas are not as unpopular as you think,
Im surprised alarm bells did not ring when i wanted to test the astroplane at the same tip height as the i-10k.
i gave you a clue when i posted that some of your ideas are not as unpopular as you think,
Im surprised alarm bells did not ring when i wanted to test the astroplane at the same tip height as the i-10k.
Hello Henry,
The right hand rule did it for me, when you explained that a light turned on, i remembered the right and left hand rules from school physics,
I realised that what i thought i was looking at in the CST plot was in fact the magnetic H field and not current phase and magnitude,
i also underestimated the effect of the height of current maxima above ground that Eddie has been telling us about for a long while,
i think the effect is magnified in this yard due to surroundings that can't be included in a model,
If it were not for snow and winds i would have had the astroplane up at the same tip height to test the idea,
i can't deny im happy you agree the sigma can outperform a 5/8wave, happy would be a gross understatement,
Still not sure what is going on when we make adjustments and see signal change other than maybe common mode currents,
my mind is made up,
i will either replace the i-10k with a rebuilt & strengthened 4 radial vector made from avanti & DX engineering tube using a fatter PTFE gamma, or have a go at building a collinear from old sirio parts.
thanks.
The right hand rule did it for me, when you explained that a light turned on, i remembered the right and left hand rules from school physics,
I realised that what i thought i was looking at in the CST plot was in fact the magnetic H field and not current phase and magnitude,
i also underestimated the effect of the height of current maxima above ground that Eddie has been telling us about for a long while,
i think the effect is magnified in this yard due to surroundings that can't be included in a model,
If it were not for snow and winds i would have had the astroplane up at the same tip height to test the idea,
i can't deny im happy you agree the sigma can outperform a 5/8wave, happy would be a gross understatement,
Still not sure what is going on when we make adjustments and see signal change other than maybe common mode currents,
my mind is made up,
i will either replace the i-10k with a rebuilt & strengthened 4 radial vector made from avanti & DX engineering tube using a fatter PTFE gamma, or have a go at building a collinear from old sirio parts.
thanks.
Hello Bob,
The more you dig into antennas the more you will find out most antennas are not performing as we think they are, and there the "key" lies.
Antenna (current) height is important.
And to know if the antennas actually does what we think it should do, which is far from reality in a lot of circumstances.
There always is a "reason" for something, the trick is to find out what that is.
Yes, you understood correct about the 5/8 wave.
I see the "battle" about the 5/8 wave and the high prices along with it.
That is something for me difficult to understand.
Lets do it otherwise..say you are interested in that big signal in your next door town.
ehm...6meter aluminium tubing costs here about 40 euro's ?
Its wise to spend that 40 euros.
Put it between the mast and your vertical antenna.
It will provide a lot more signal strength on the distant horizon then changing into a 300 euro versions or whatever the I10K etc. cost.
There is one "catch" just make sure your present antenna is performing as it should.
Kind regards, H>
The more you dig into antennas the more you will find out most antennas are not performing as we think they are, and there the "key" lies.
Antenna (current) height is important.
And to know if the antennas actually does what we think it should do, which is far from reality in a lot of circumstances.
There always is a "reason" for something, the trick is to find out what that is.
Yes, you understood correct about the 5/8 wave.
I see the "battle" about the 5/8 wave and the high prices along with it.
That is something for me difficult to understand.
Lets do it otherwise..say you are interested in that big signal in your next door town.
ehm...6meter aluminium tubing costs here about 40 euro's ?
Its wise to spend that 40 euros.
Put it between the mast and your vertical antenna.
It will provide a lot more signal strength on the distant horizon then changing into a 300 euro versions or whatever the I10K etc. cost.
There is one "catch" just make sure your present antenna is performing as it should.
Kind regards, H>
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Well Bob, I was thinking that you were waiting on DB to report some new ideas based on his 4Nec2 model of a NV4K.
I was also surprised at you re-thinking about the performance of the AstroPlane after all those years. I thought you just got a good deal on an original. BTW, you don't have to measure your new/old antenna for me. Somebody posted or emailed me the sheet I was missing in the A/P manual and all of the dimensions are there.
Bob, I hope for the best, but I think no matter what your efforts at testing the performance of the A/P will show...the fact that Sirio has stopped production of their New Top One design...pretty much nails the coffin shut on any future for the old Avanti idea, and contrary to popular belief...I find the New Top One just as effective if not a bit better in raw gain than my original A/P model at the same height.
When I averaged several months of signal reports in my real world testing with contacts that ranged from 15-80 miles several years ago...my NTO also showed an average Suint signal of 7.2 vs 7.0 for my Old Top One, while reporting signal results for at least 8 regular contacts in all directions from me.
It is a shame too, because the design is a very effective antenna IMO...as only a center fed dipole can be, and this one does not require any matching so matching losses are minimal. I don't think many folks believe it matters a hoot, but my A/P models also produce the best shaped patterns of any of my CB antennas and they look to cover the best part of the really productive areas around the horizon.
I am hopeful that my recent repeated bad experiences with TVI currents...was just another mis-que in my observations here at my location too, and I hope you can help me prove or disprove this idea. This is not the first time this has happened for me, but it is the first time I've talked about it. Several years ago I did a video showing this happening on my OTO, but nobody ever commented, so I left the idea alone. The old A/P has already received quite enough bad press in the past without my adding a idea about terrible feed line radiation to the mix of misinformation.
I was also impressed at Henry's observations on antenna height and what happens to gain across the frequency bandwidth. See his chart on page 34, in his report. I never understood this effect, but I know now what I was noticing and for sure when I noticed it with my models. IMO, there is something about antenna symmetry and balance that we too often tend to consider as just plain vanilla in an antenna design. Just another thing that really affects the results we tend not to hear about when comparing CB antennas that are not new and/or sexy by design.
Henry, I don't think I have a foundation for these questions, but can I ask you for some more info about the model that GHZ24 did in your report?
My maximum antenna gain is close to what he shows in his free space model, but my Eznec model shows a much lower angle than he reports. His model also suggest that he modeled the cone with very short radials and a wide diameter hoop I think. You tell us that he used the optimization feature, so this may account for these difference noted, but why was it important to use this out of specs version?
Will you be reporting on the stacked collinear test that you ran as well? The foundation for this question is based on Bob telling me that the next thing on his agenda, after the A/P, may be doing something with a real stacked collinear antennas using the Vector.
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Hello Eddie,
The model used for gain figures etc is an copy of the commercial availible antenna.
Im not going to say witch one, but i used several availible types.
The reason im not going to is:
Im confident there will be a manufacturer "claiming"
owh well...he used antenna "a",
But if you try my antenne "b" you will find out it is working better.
That is ...well it is what manufacturers do hihi.
They will try to find a escape capsule...they will tell stories that can not be true.
For commercial reasons or the fact that they dont understand themself.
The model used for the cone as a dummyload etc isnt a exact copy of course.
The model provided by GHZ24 has been given for the primairy reasons.
The model allows you to change all "settings" without to re-write everything hand by hand. It was allready online here on the forum, and i thougth it would honor his efforts. It would give insight on how to work with 4nec2 and its optimiser settings.
With that said, I didnt use it...
I provided it, cause im sure there will be those who will not understand and want to inverstigate "best"' angle..."best" height" etc etc.
The GHZ24 model can "help" with that.
Perhaps ill add some other models to the story as well.
No Eddy, I didnt tell you he used the Optimiser settings.
That is your interpertation. My intention is to say "it allows you to".
The extra 1/2 wave collinear story might come up.
But it sure was fun to do !
Im sorry i have to be carefull with my words, as if I say yes...
It means i will have to, and i just found out writing a long article takes a lot of time hihi.
Kind regards,
Henry
The model used for gain figures etc is an copy of the commercial availible antenna.
Im not going to say witch one, but i used several availible types.
The reason im not going to is:
Im confident there will be a manufacturer "claiming"
owh well...he used antenna "a",
But if you try my antenne "b" you will find out it is working better.
That is ...well it is what manufacturers do hihi.
They will try to find a escape capsule...they will tell stories that can not be true.
For commercial reasons or the fact that they dont understand themself.
The model used for the cone as a dummyload etc isnt a exact copy of course.
The model provided by GHZ24 has been given for the primairy reasons.
The model allows you to change all "settings" without to re-write everything hand by hand. It was allready online here on the forum, and i thougth it would honor his efforts. It would give insight on how to work with 4nec2 and its optimiser settings.
With that said, I didnt use it...
I provided it, cause im sure there will be those who will not understand and want to inverstigate "best"' angle..."best" height" etc etc.
The GHZ24 model can "help" with that.
Perhaps ill add some other models to the story as well.
No Eddy, I didnt tell you he used the Optimiser settings.
That is your interpertation. My intention is to say "it allows you to".
The extra 1/2 wave collinear story might come up.
But it sure was fun to do !
Im sorry i have to be carefull with my words, as if I say yes...
It means i will have to, and i just found out writing a long article takes a lot of time hihi.
Kind regards,
Henry
Henry, if I had a question about the models or programs you used in your report for gain figures...I would have been specific in the information I wanted.
I asked specifically about the model that you posted from GHZ24, and I just wondered why it does not look to be to specs for the Vector 4000 that this report is all about, and what its significance is to your project. It violates all the efforts you made in explaining how a good model might look and be well constructed as noted on pages 9-10, of your report.
Never mind, explaining why you noted this particular model in your introduction. I went back in the record and found his post, and GHZ24 admits that his model was set with <>60" radials, the hoop was very wide with a hoop diameter set close to 60" inches not at 15" radius like the real Vector design.
To me, this idea put into its real context...looks like GHZ24 moded the old idea that Donald presented earlier...when Donald was telling us all that a more spread out radial design would produce better gain, etc. According to Bob, Donald even built a real model of his idea he claims comes straight from the Avanti Patent. I don't think we know what the results really were, because the idea just seemed to ceased being discussed.
IMO, Donald got that idea wrong too. Henry, I understand what it sometimes means to get my thinking wrong, and find I have to change my mind. I've been soundly criticized for changing my mind about how the Sigma4 design works, and now it looks like the shoe is on the other foot...so to speak.
Here is the model that I asked about from GHZ24. Put into context of what he said about it...his idea was not to build a Vector 4000 to specs...but he did not say specifically why he did what he did in that design. I tend to believe he was trying to duplicate what Donald was telling us...as I've noted above.
Just to be clear, here is the model you posted in the introduction to your report that I converted to feet and inches in Free Space at 27.205 mhz. I've also added an overlay of the radiated pattern as a comparison of the Vector 4000 vs. a simple Center fed 1/2 wave dipole in my own library. You also told me you didn't use it, right?
Also take note the GHZ24's Vector pattern is very similar to the model pattern results you posted in your report at the top of page 30, where you compare results from a CST model, and your own center fed dipole at the bottom of page 28. I have no issues with the details here, they are of little consequenceto me, but I'm probably the only one that would ever question anything you say here, so respond if you can.
Haw Henry, sometimes it is better to use a little Honey. Some wise words I thought a friend appropriately brought to my attention once...when out of frustration I was out of step with others on this very topic.
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Thanks so much for the work you put into the article.
I have championed the V4k style antennas and argued many of the points you brought up.
Ironically, I have lately settled on the use of a simple vertical 1/2 wave dipole fed with the coax up through the bottom of the lower tube to the center. While I am convinced of the superior results I saw with the V4k over other antennas used I nevertheless became convinced that the DX I prefer to work over local and distant local rag chewing is so propagation conditions dependent that I have reduced my aerial signature to smaller antennas with the current maximum in the most advantaged position I can achieve.
I especially enjoyed the part of the article that responded to the tip height discussion (ergo the Astroplane). All of it was great.
Overall, I find the article landing in the camp of those who say the Sigma IV/V4k antennas are J-poles, or did I miss something?
Homer
I have championed the V4k style antennas and argued many of the points you brought up.
Ironically, I have lately settled on the use of a simple vertical 1/2 wave dipole fed with the coax up through the bottom of the lower tube to the center. While I am convinced of the superior results I saw with the V4k over other antennas used I nevertheless became convinced that the DX I prefer to work over local and distant local rag chewing is so propagation conditions dependent that I have reduced my aerial signature to smaller antennas with the current maximum in the most advantaged position I can achieve.
I especially enjoyed the part of the article that responded to the tip height discussion (ergo the Astroplane). All of it was great.
Overall, I find the article landing in the camp of those who say the Sigma IV/V4k antennas are J-poles, or did I miss something?
Homer